Apparatus, systems, and methods for providing a hybrid voltage regulator

ABSTRACT

The present disclosure shows a hybrid regulator topology that can be more easily integrated and that can maintain high efficiency across a wide output and input voltage range, even with a small inductor. The hybrid regulator topology can include two types of regulators: a flying switched-inductor regulator and a step-down regulator that divides the input voltage into an M/N fraction of the input voltage. The disclosed embodiments of the hybrid regulator topology can reduce the capacitive loss of the flying switched-inductor regulator by limiting the voltage swing across the switches in the flying switched-inductor regulator. The disclosed embodiments of the hybrid regulator topology can reduce the inductor resistive loss of the flying switched-inductor regulator by operating the flying switched-inductor regulator at a high switching frequency and with a small amount of current flow through the inductor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of the earlier filing date, under 35U.S.C. § 119(e), of U.S. Provisional Application No. 61/810,998, filedon Apr. 11, 2013, entitled “SYSTEMS AND METHODS FOR PROVIDING A HYBRIDVOLTAGE REGULATOR”, which is herein incorporated by reference in itsentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under 1248828 awarded bythe National Science Foundation (NSF). The government has certain rightsin the invention.

TECHNICAL FIELD

The present disclosure relates to apparatus, systems, and methods forproviding a hybrid voltage regulator.

BACKGROUND

There is a strong demand to reduce the size of electronic systems. Thesize reduction is especially desirable in mobile electronics where spaceis a premium, but is also desirable in servers that are placed in bigdata centers since it is important to squeeze in as many servers aspossible in a fixed real estate.

One of the largest components in electronic systems includes voltageregulators (sometimes also referred to as power regulators). A voltage(or power) regulator is designed to convert a source voltage of a sourcevoltage signal to a target voltage so that the target voltage can servean output load of the voltage/power regulator. Power regulators ofteninclude a large number of bulky off-chip components to deliver voltagesto integrated chips, including processors, memory devices (e.g., adynamic read access memory (DRAM)), radio-frequency (RF) chips, WiFicombo chips, and power amplifiers. Therefore, it is desirable to reducethe size of the voltage regulators in electronic systems.

Power regulators include semiconductor chips, such as a DC-DC regulatorchip, that deliver power from a power source (e.g., a battery) to anoutput load. The output load can include a variety of integrated chips(e.g., an application processor, a DRAM, a NAND flash memory) in anelectronic device. To efficiently deliver power, a voltage regulator canuse a “buck” topology. Such a regulator is referred to as a buckregulator. A buck regulator transfers charges from the power source tothe output load using an inductor. A buck regulator can use powerswitches to connect/disconnect the inductor to one of multiple voltages,thereby providing an output voltage that is a weighted average of themultiple voltages. A buck regulator can adjust the output voltage bycontrolling the amount of time the inductor is coupled to one of themultiple voltages.

Unfortunately, a buck regulator is not suitable for highly integratedelectronic systems. The conversion efficiency of a buck regulatordepends on the size of the inductor, in particular when the powerconversion ratio is high and when the amount of current consumed by theoutput load is high. Because an inductor can occupy a large area and isbulky to integrate on-die or on-package, existing buck regulators oftenuse a large number of off-chip inductor components. This strategy oftenrequires a large area on the printed circuit board, which in turnincreases the size of the electronic device. The challenge isexacerbated as mobile system-on-chips (SoCs) become more complex andneed increasingly larger number of voltage domains to be delivered bythe voltage regulator.

SUMMARY

Some embodiments of the disclosed subject matter include a voltageregulator. The voltage regulator is configured to receive a firstvoltage signal and provide a final voltage signal based, at least inpart, on the first voltage signal. The voltage regulator includes aflying switched-inductor regulator having a first input terminalconfigured to receive a first voltage signal, a second input terminalconfigured to receive a second voltage signal, and an output terminalconfigured to provide an intermediate voltage signal based, at least inpart, on the first voltage signal and the second voltage signal; astep-down regulator comprising an input terminal, coupled to the outputterminal of the flying switched-inductor regulator, an output terminal,and a plurality of capacitors, wherein the step-down regulator isconfigured to receive, at the input terminal of the step-down regulator,the intermediate voltage signal from the output terminal of the flyingswitched-inductor regulator and provide, to the output terminal of thestep-down regulator, the final voltage signal using a predeterminedconfiguration of the plurality of capacitors; and a level shiftingregulator comprising an input terminal, an output terminal, a flyingcapacitor, and a plurality of switches, wherein the level shiftingregulator is configured to receive, at the input terminal of the levelshifting regulator, the final voltage signal of the step-down regulatorand to provide, at the output terminal of the level shifting regulator,the second voltage signal that is based on the final voltage signal ofthe step-down regulator.

In some embodiments of the voltage regulator disclosed herein, the levelshifting regulator can be configured to change a configuration of theplurality of switches to provide the flying capacitor in parallel withthe first input terminal and the second input terminal of the flyingswitched-inductor regulator.

In some embodiments of the voltage regulator disclosed herein, the levelshifting regulator can be configured to change a configuration of theplurality of switches to provide the flying capacitor in parallel withthe output terminal of the step-down regulator and ground.

In some embodiments of the voltage regulator disclosed herein, theflying switched-inductor regulator can include an inductor having aninductance within a range of 100 pico-Henry and 1 micro-Henry.

In some embodiments of the voltage regulator disclosed herein, at leastone of the plurality of capacitors in the step-down regulator can befabricated using a dynamic random access memory (DRAM) fabricationprocess.

In some embodiments of the voltage regulator disclosed herein, theflying switched-inductor regulator can include a plurality of regulatorsconfigured to operate in parallel in a time interleaved manner.

In some embodiments of the voltage regulator disclosed herein, theflying switched-inductor regulator can be configured to operate at afirst switching frequency, and the step-down regulator can be configuredto operate at a second switching frequency.

In some embodiments of the voltage regulator disclosed herein, thevoltage regulator can also include a first control loop configured toregulate the final voltage signal of the step-down regulator, and asecond control loop configured to regulate the intermediate voltagesignal of the flying switched-inductor regulator.

In some embodiments of the voltage regulator disclosed herein, the firstcontrol loop can be configured to operate the step-down regulator toprovide a fraction of the intermediate voltage signal at the output nodeso that the step-down regulator operates in a configuration providing ahigh conversion efficiency.

In some embodiments of the voltage regulator disclosed herein, the firstcontrol loop can be configured to operate the step-down regulator tocause the final voltage signal of the step-down regulator to be within apredetermined error range of a target output voltage.

In some embodiments of the voltage regulator disclosed herein, theflying switched-inductor regulator and the step-down regulator,excluding the inductor of the flying switched-inductor regulator, can beprovided in a single die.

In some embodiments of the voltage regulator disclosed herein, theinductor can be provided as a discrete component on-package or on-board.

Some embodiments of the disclosed subject matter include an electronicsystem. The electronic system can include some embodiments of thevoltage regulator disclosed herein. The electronic system can alsoinclude a target load system coupled to the voltage regulator, whereinthe output terminal of the step-down regulator in the voltage regulatoris coupled to the target load system.

In some embodiments of the electronic system disclosed herein, thetarget load system can include a battery and the voltage regulator canbe configured to receive the first voltage signal from a power line of aUniversal Serial Bus and to provide the final voltage signal to thebattery.

In some embodiments of the electronic system disclosed herein, thetarget load system can include a System on Chip (SoC), and the SoC andthe voltage regulator can be packaged in a single SoC package.

In some embodiments of the electronic system disclosed herein, thetarget load system can include a System on Chip (SoC), and the SoC andthe voltage regulator can be provided on a printed circuit board (PCB).

Some embodiments of the disclosed subject matter include an electronicsystem. The electronic system can include an embodiment of a voltageregulator disclosed herein, wherein the voltage regulator is configuredto operate in a reverse direction in which the output terminal of thestep-down regulator in the voltage regulator is coupled to an inputvoltage source and the first input terminal of the flyingswitched-inductor regulator is coupled to a target load of the voltageregulator.

In some embodiments of the electronic system disclosed herein, theelectronic system operating the voltage regulator in a reverse directioncan be configured to operate the voltage regulator as a step-upregulator.

In some embodiments of the electronic system disclosed herein, theoutput terminal of the step-down regulator can be coupled to a batteryand the first input terminal of the flying switched-inductor regulatorcan be coupled to a power line of a Universal Serial Bus.

Some embodiments of the disclosed subject matter includes a method ofconverting an first voltage signal to a final voltage signal using avoltage regulator comprising a flying switched-inductor regulator and astep-down regulator. The method can include receiving the first voltagesignal at a first input terminal of the flying switched-inductorregulator and a second voltage signal at a second input terminal of theflying switched-inductor regulator; providing, at an output terminal ofthe flying switched-inductor regulator, an intermediate voltage signalbased, at least in part, on the first voltage signal and the secondvoltage signal; providing, to an output terminal of a step-downregulator using a predetermined configuration of a plurality ofcapacitors in the step-down regulator, the final voltage signal based onthe intermediate voltage signal; and receiving, at an input terminal ofa level shifting regulator, the final voltage signal and providing,using the level shift regulator, to the second input terminal of theflying switched-inductor regulator, the second voltage signal determinedbased on the final voltage signal, forming a feedback path between theoutput terminal of the step-down regulator and the second input terminalof the flying switched-inductor regulator.

In some embodiments of the method disclosed herein, the level shiftingregulator can include a flying capacitor and a plurality of switches,and the method can include providing the flying capacitor in parallelwith the first input terminal and the second input terminal of theflying switched-inductor regulator by modifying a configuration of theplurality of switches.

In some embodiments of the method disclosed herein, the level shiftingregulator can include a flying capacitor and a plurality of switches,and the method can further include providing the flying capacitor inparallel with the output terminal of the step-down regulator and groundby modifying a configuration of the plurality of switches.

Some embodiments of the disclosed subject matter includes a voltageregulator configured to receive a first voltage signal and provide asecond voltage signal based, at least in part, on the first voltagesignal. The voltage regulator can include a receiving regulatorcomprising an inductor, wherein the receiving regulator is configured toreceive the first voltage signal at a first terminal of the inductor andto provide an intermediate voltage signal at a second terminal of theinductor based, at least in part, on the first voltage signal; and astep-down regulator comprising a plurality of input terminals and anoutput terminal, wherein the step-down regulator is configured toreceive, at one of the plurality of input terminals, the intermediatevoltage signal from the second terminal of the inductor for a portion ofa time period, and to provide the second voltage signal at the outputterminal based on the received intermediate voltage signal.

In some embodiments of the voltage regulator disclosed herein, thevoltage regulator can further include a plurality of switches configuredto couple the second terminal of the inductor to at least one of theplurality of input terminals.

In some embodiments of the voltage regulator disclosed herein, a firstswitch of the plurality of switches is configured to couple the secondterminal of the inductor to a first input terminal of the plurality ofinput terminals, wherein a second switch of the plurality of switches isconfigured to couple the second terminal of the inductor to a secondinput terminal of the plurality of input terminals, and the first switchand the second switch are turned on in a time-multiplexed manner.

In some embodiments of the voltage regulator disclosed herein, thestep-down regulator is configured to reduce a voltage at the first inputterminal by a first amount and reduce a voltage at the second inputterminal by a second amount different from the first amount.

In some embodiments of the voltage regulator disclosed herein, thevoltage regulator can include a controller configured to control a dutycycle of the first switch and the second switch to control the secondvoltage signal of the voltage regulator.

In some embodiments of the voltage regulator disclosed herein, thestep-down regulator can include a plurality of switched capacitorregulators.

In some embodiments of the voltage regulator disclosed herein, thereceiving regulator and the plurality of switches can form a flyingswitched-inductor regulator.

In some embodiments of the voltage regulator disclosed herein, thestep-down regulator and the plurality of switches can form a switchedcapacitor regulator.

In some embodiments of the voltage regulator disclosed herein, thereceiving regulator can include a shunt switch that is configured toshort the inductor when the voltage regulator is initially powered up toreduce an inrush current.

In some embodiments of the voltage regulator disclosed herein, thereceiving regulator can include a series switch in series with theinductor, wherein the series switch is configured to decouple theinductor from the first switch and the second switch when the voltageregulator is initially powered up to reduce an inrush current.

In some embodiments of the voltage regulator disclosed herein, thevoltage regulator can include a shunt regulator configured to increase avoltage at the second terminal of the inductor when the voltageregulator is initially powered up to reduce an inrush current.

In some embodiments of the voltage regulator disclosed herein, thevoltage regulator can include a shunt regulator configured to increase avoltage at one of nodes within the step-down regulator when the voltageregulator is initially powered up to reduce an inrush current.

In some embodiments of the voltage regulator disclosed herein, thestep-down regulator comprises at least one capacitor, and the at leastone capacitor is fabricated using a dynamic random access memory (DRAM)fabrication process.

Some embodiments of the disclosed subject matter include an electronicsystem. The electronic system includes a voltage regulator in accordancewith some embodiments, and a target load system coupled to the voltageregulator, wherein the output terminal of the switched capacitorregulator in the voltage regulator is coupled to the target load system.

In some embodiments of the electronic system disclosed herein, thetarget load system includes a battery and the voltage regulator isconfigured to receive the first voltage signal from a power line of aUniversal Serial Bus and to provide the second voltage signal to thebattery to charge the battery using the power line of the UniversalSerial Bus.

Some embodiments of the disclosed subject matter include an electronicsystem. The electronic system can include a voltage regulator inaccordance with some embodiments, where the voltage regulator isconfigured to operate in a reverse direction in which the outputterminal of the switched capacitor regulator in the voltage regulator iscoupled to an input voltage source and the first terminal of theinductor in the receiving regulator is coupled to a target load of thevoltage regulator.

In some embodiments of the electronic system disclosed herein, theelectronic system operating the voltage regulator in a reverse directionis configured to operate the voltage regulator as a step-up regulator.

In some embodiments of the electronic system disclosed herein, theoutput terminal of the switched capacitor regulator in the voltageregulator is coupled to a battery and the first terminal of the inductorin the receiving regulator is coupled to a power line of a UniversalSerial Bus.

Some embodiments of the disclosed subject matter includes a method ofconverting an first voltage signal to a second voltage signal using avoltage regulator comprising a receiving regulator and a switchedcapacitor regulator. The method can include receiving, at a firstterminal of an inductor in the receiving regulator, the first voltagesignal; providing, at a second terminal of the inductor, an intermediatevoltage signal based, at least in part, on the first voltage signal;coupling the second terminal of the inductor to one of a plurality ofinput terminals of the step-down regulator to provide the intermediatevoltage signal to the one of the plurality of input terminals; andconverting the intermediate voltage signal, at the one of the pluralityof input terminals, into the second voltage signal using the step-downregulator.

In some embodiments of the method disclosed herein, one of the pluralityof input terminals is coupled to ground.

In some embodiments of the method disclosed herein, the method caninclude coupling, via a first switch for a first duration, the secondterminal of the inductor to a first input terminal of the plurality ofinput terminals, and coupling, via a second switch for a secondduration, the second terminal of the inductor to a second input terminalof the plurality of input terminals.

In some embodiments of the method disclosed herein, the method caninclude controlling a ratio of the first duration and the secondduration to control the second voltage signal.

In some embodiments of the method disclosed herein, the method caninclude shorting the first terminal and the second terminal of theinductor using a shunt switch when the voltage regulator is initiallypowered up to reduce an inrush current.

In some embodiments of the method disclosed herein, the method caninclude increasing a voltage at the second terminal of the inductorusing a shunt regulator when the voltage regulator is initially poweredup to reduce an inrush current.

In some embodiments of the method disclosed herein, the output terminalof the switched capacitor regulator in the voltage regulator can becoupled to an input voltage source and the first terminal of theinductor in the receiving regulator can be coupled to a target load ofthe voltage regulator to operate the voltage regulator in a reversedirection.

There has thus been outlined, rather broadly, the features of thedisclosed subject matter in order that the detailed description thereofthat follows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the disclosed subject matter that will bedescribed hereinafter and which will form the subject matter of theclaims appended hereto.

In this respect, before explaining at least one embodiment of thedisclosed subject matter in detail, it is to be understood that thedisclosed subject matter is not limited in its application to thedetails of construction and to the arrangements of the components setforth in the following description or illustrated in the drawings. Thedisclosed subject matter is capable of other embodiments and of beingpracticed and carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein are for the purposeof description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, systems, methods and media forcarrying out the several purposes of the disclosed subject matter. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the disclosed subject matter.

These together with the other objects of the disclosed subject matter,along with the various features of novelty which characterize thedisclosed subject matter, are pointed out with particularity in theclaims annexed to and forming a part of this disclosure. For a betterunderstanding of the disclosed subject matter, its operating advantagesand the specific objects attained by its uses, reference should be hadto the accompanying drawings and descriptive matter in which there areillustrated preferred embodiments of the disclosed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects, features, and advantages of the disclosed subjectmatter can be more fully appreciated with reference to the followingdetailed description of the disclosed subject matter when considered inconnection with the following drawings, in which like reference numeralsidentify like elements.

FIGS. 1A-1B illustrate a buck regulator and its operation.

FIGS. 2A-2B illustrate a voltage regulator that includes a step-downregulator at the first-stage and an inductor-based buck regulator at thesecond stage.

FIG. 3 illustrates a high-level diagram of a voltage regulator thatincludes a flying switched-inductor regulator at the first stage and astep-down regulator at the second stage, in accordance with someembodiments.

FIGS. 4A-4B illustrate a detailed schematic diagram of FIG. 3 in whichthe flying switched-inductor regulator at the first stage includes aflying buck regulator, in accordance with some embodiments.

FIGS. 5A-5D illustrate a detailed schematic diagram and its operation ofFIG. 3 in which the flying switched-inductor regulator at the firststage includes a flying buck regulator with a flying capacitor inaccordance with some embodiments.

FIGS. 6A-6B illustrate a detailed schematic diagram of FIG. 3 in whichthe flying switched-inductor regulator at the first stage includes aflipped flying buck regulator in accordance with some embodiments.

FIGS. 7A-7B illustrate a detailed schematic diagram of FIGS. 6A-B inwhich the N:M regulator includes a switched-capacitor regulator inaccordance with some embodiments.

FIGS. 8A-B illustrate a block diagram showing configurations of aninductor coupled to a voltage regulator chip in accordance with someembodiments.

FIG. 9 shows a block diagram of a feedback control system for a voltageregulator in accordance with some embodiments.

FIG. 10 shows a block diagram of a feedback control system for a voltageregulator in accordance with some embodiments.

FIG. 11 illustrates how a duty cycle of a flying switched-inductorregulator and a conversion ratio of the step-down regulator changeacross output voltages in accordance with some embodiments.

FIG. 12 illustrates how a duty cycle of the flying switched-inductorregulator and a conversion ratio of the step-down regulator changesacross output voltages in accordance with some embodiments.

FIG. 13 illustrates a hybrid converter in a step-up configuration inaccordance with some embodiments.

FIGS. 14A-14B illustrate an operation of a hybrid converter in a step-upconfiguration in accordance with some embodiments.

FIGS. 15A-15B illustrate a hybrid converter including a flyingswitched-inductor regulator in a step-up configuration in accordancewith some embodiments.

FIGS. 16A-16B illustrate an operation of a hybrid regulator having aflying switched-inductor regulator in accordance with some embodiments.

FIG. 17 shows a hybrid converter that can provide both step-down andstep-up voltage regulation in accordance with some embodiments.

FIG. 18 is a cross-section view of an integrated voltage regulator inaccordance with some embodiments.

FIG. 19 is a cross-section view of an integrated voltage regulator inaccordance with some embodiments.

FIG. 20 is a cross-section view of an integrated voltage regulator witha discrete inductor component in accordance with some embodiments.

FIG. 21 is a cross-section view of an integrated voltage regulator witha discrete inductor component in accordance with some embodiments.

FIG. 22 is a cross-section view of integrated voltage regulator diesplaced next to an system-on-chip (SoC) die in an SoC package inaccordance with some embodiments.

FIG. 23 is a cross-section view of integrated voltage regulator dies anddiscrete inductor components placed next to an SoC die in an SoC packagein accordance with some embodiments.

FIG. 24 is a cross-section view of an integrated voltage regulator dieor package placed next to an SoC package on a printed circuit board(PCB) in accordance with some embodiments.

FIG. 25 is a cross-section view of an integrated voltage regulator dieor package and discrete inductor component placed next to an SoC packageon a PCB in accordance with some embodiments.

FIG. 26 is a top view of large numbers of small integrated voltageregulator dies placed next to an SoC package on a PCB in accordance withsome embodiments.

FIG. 27 is a top view of few, large integrated voltage regulator diesplaced next to an SoC package on a PCB in accordance with someembodiments.

FIG. 28 illustrates a hybrid regulator having a flying switched-inductorregulator with a shunt switch in accordance with some embodiments.

FIG. 29 illustrates a hybrid regulator having a flying switched-inductorregulator with a series switch and a shunt switch in accordance withsome embodiments.

FIG. 30 illustrates a hybrid regulator having a shunt regulator as astart-up circuitry in accordance with some embodiments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forthregarding the systems and methods of the disclosed subject matter andthe environment in which such systems, methods and media may operate,etc., in order to provide a thorough understanding of the disclosedsubject matter. It will be apparent to one skilled in the art, however,that the disclosed subject matter may be practiced without such specificdetails, and that certain features, which are well known in the art, arenot described in detail in order to avoid complication of the disclosedsubject matter. In addition, it will be understood that the examplesprovided below are exemplary, and that it is contemplated that there areother systems and methods that are within the scope of the disclosedsubject matter.

Modern electronic systems have been tightly integrated as asystem-on-chip (SoC) that incorporates multiple processing cores andheterogeneous components (e.g., memory controllers, hardwareaccelerators) within a single chip. The popularity of SoCs, coupled withtighter power budgets, motivates controlling the voltage and frequencyat a block-specific granularity. The block-specific voltage control canallow the electronic system to raise only the voltage of the core(s)that desires higher performance. Such a block-specific voltage controlcan improve power and/or performance.

However, traditional approaches of dynamic voltage and frequency scaling(DVFS) have been performed at a coarse-grain level due to cost and sizelimitations of off-chip voltage regulators. Moreover, traditional DVFSschemes were limited to a slow voltage/frequency scaling at themicro-second timescale due to the slow speed of off-chip voltageregulators. Faster DVFS in nano-second timescale can save significantlymore power consumed by the SoC by closely tracking the SoC voltage tothe rapidly changing computation demand.

Given these drawbacks of off-chip voltage regulators, there has been asurge of interest in building integrated voltage regulators (IVR) toreduce board size and enable nanosecond timescale, per-core DVFS. An IVRcan include a variety of voltage regulators, including a switchingregulator and a low-dropout linear regulator. IVRs that can reduce theboard size and can enable nanosecond timescale, per-core DVFS aredisclosed in articles authored by inventors of the present application,including an article entitled “System Level Analysis of Fast, Per-CoreDVFS using On-Chip Switching Regulators,” published in IEEEInternational Symposium on High-Performance Computer Architecture (HPCA)in February 2008, by Wonyoung Kim et al.; an article entitled “DesignTechniques for Fully Integrated Switched-Capacitor DC-DC Converters,”published in IEEE Journal of Solid-State Circuits (JSSC) in September2011, by Hanh-Phuc Le et al.; and an article entitled “AFully-Integrated 3-Level DC/DC Converter for Nanosecond-Scale DVFS,”published in IEEE Journal of Solid-State Circuits (JSSC) in January2012, by Wonyoung Kim et al., each of which is hereby incorporatedherein by reference in its entirety.

A switching regulator can include a buck regulator. FIGS. 1A-1Billustrate a buck regulator and its operation. As illustrated in FIG.1A, the buck regulator 100 can include an inductor 108 and two switches114, 116. The buck regulator 100 can connect the inductor 108 to a firstvoltage source V_(IN) 104 and a second voltage source 118 through a setof power switches 114, 116. In some cases, the second voltage source 118can include a ground voltage source. The power switches 114, 116 can beturned on and off using external inputs. In some cases, the powerswitches 114, 116, can be controlled so that the two switches are notturned on at the same time. The power switches 114, 116 can includetransistors. The transistors can include a MOSFET transistor. Forexample, the switch 114 can include a P-channel MOSFET transistor; theswitch 116 can include an N-channel MOSFET transistor.

As illustrated in FIG. 1B, as the power switches 114, 116 turn on andoff with a period T, the input of the inductor V_(X) 102 can swingbetween 0 and V_(IN) with a period T. The inductor 108 and capacitor 120operate as a low-pass filter that averages V_(X) 102 over time, therebycreating a signal at the regulator output V_(OUT) 110 with a smallvoltage ripple. The output voltage V_(OUT) 110 can depend on the amountof time the inductor 108 is coupled to the first voltage source V_(IN)104 and the amount of time the inductor 108 is coupled to the secondvoltage source 118. For example, the buck regulator 100 can adjust thelevel of V_(OUT) 510 to V_(IN)D+(0V)(1−D), where D, a number between 0and 1, is the portion of time V_(X) is coupled to V_(IN). D is alsoreferred to as a duty cycle. The output load that consumes the current106 can be any type of an electronic device, including processors,memory (DRAM, NAND flash), RF chips, WiFi combo chips, and poweramplifiers.

The efficiency η of the buck regulator 100 can be computed as:

$\eta = \frac{P_{L}}{P_{O}}$where P_(L) indicates the power delivered to the output load 106 andP_(O) indicates the output power of the buck regulator 108. P_(L) can becomputed as follows: P_(L)=P_(O)−P_(LOSS), where P_(LOSS) includes theamount of power losses during the voltage regulation process.

One of the major power losses P_(LOSS) associated with a buck regulator100 includes a resistive loss P_(R) incurred by the parasitic resistanceof the inductor 108. When the buck regulator 100 delivers power to theoutput load 106 by providing current 112, ideally, the buck regulator100 provides all of its output power to the output load 106. However, ina practical scenario, the buck regulator 100 dissipates some of itsoutput power internally at the inductor 108. Ideally, an inductor 108has zero resistance. Therefore, a current through the inductor 108 wouldnot dissipate any power. However, in a practical scenario, an inductor108 is associated with a finite resistance, primarily due to theresistance of the material forming the inductor 108. This undesirable,finite resistance of the inductor 108 is referred to as a parasiticresistance. The parasitic resistance can incur a resistive power losssince the parasitic resistance can cause the current through theinductor 108 to dissipate energy. Therefore, the resistive power losscan reduce the power conversion efficiency of the buck regulator 100.

When the current is alternating, then the resistive power loss can becomputed as P_(R)=I_(L,RMS) ²R_(L), where R_(L), is the value of theparasitic resistance of the inductor 108, and I_(L,RMS) is the root-meansquare of the current through the inductor 108. I_(L,RMS) can be reducedby reducing the peak-to-peak ripple of the inductor current (I_(L,PP)120). Therefore, the buck regulator 100 can reduce the resistive lossP_(R) by reducing the peak-to-peak ripple of the inductor currentI_(L,PP) 120.

There are two ways to reduce the peak-to-peak ripple of the inductorcurrent I_(L,PP) 120. First, the buck regulator 100 can switch at a highfrequency and reduce the period of the switching regulator T. However,this solution can increase the power consumed to charge and dischargethe parasitic capacitance at the junction 122 between switches 114, 116.This capacitive power loss can be significant because the size of theswitches 114, 116 can be large, which increases the parasiticcapacitance, and because the voltage swing on V_(X) 102 is large. Thiscapacitive power loss can be computed as follows: P_(C)=fCV², where f isthe frequency at which the buck regulator 100 switches, C is the amountof the parasitic capacitance at the junction 122, and V is the voltageswing at the junction 122. This power loss can be significant becausethe size of the switches 114, 116 is large, which increases theparasitic capacitance, and because the voltage swing on V_(X) 102 islarge.

Second, the buck regulator 100 can use an inductor 108 with a highinductance value, thereby reducing the parasitic resistance R_(L).However, this approach makes the inductor 108 large and makesintegration difficult.

A switching regulator can also include a switched-capacitor (SC)regulator. An SC regulator can use one or more capacitors, instead ofinductors, to transfer charges from a power source to an output load. AnSC regulator can use power switches to coupled/disconnect one or morecapacitors to one of multiple voltages, thereby providing an outputvoltage that is a weighted average of the multiple voltages. The SCregulator can control the output voltage by changing the configurationand the sequence in which capacitors are coupled to one another. Becausecapacitors are easier to integrate on-die or on-package than inductors,it is easier to implement SC IVRs with a small size.

However, efficiencies of SC regulators can degrade at output voltagesthat are not a predetermined fraction of the input voltage. For example,a SC regulator can achieve high efficiencies at ½, ⅓, ⅔, ⅖, ⅗ of theinput voltage. However, the same SC regulator can fail to provide highefficiencies when the output voltage deviates from those values. This isa problem for many SoCs that operate within a continuous range ofvoltages, or a range of voltages in 5-10 mV steps.

Some of the challenges associated with the SC regulator can be addressedby operating the SC regulator to provide an output voltage at which theSC regulator can provide a high efficiency, and subsequently regulatingthe output voltage of the SC regulator using a buck converter. FIGS.2A-2B illustrate a power converter that includes an SC regulator and abuck regulator in two stages. FIG. 2A includes an SC regulator 222 and abuck regulator 100. The SC regulator 222 can convert the input voltage104 to V_(TMP) 224, which is a fraction of the input voltage at whichthe SC regulator can provide high efficiency. For example, V_(TMP) 224can be V_(IN)/N, where N is the step-down ratio. Then the buck regulator100 can receive V_(TMP) 224 and regulate it to provide V_(OUT) 210 infine steps using multiple power switches 114, 116 and one or moreinductors 108. FIG. 2B illustrates the timing diagram of signals in theregulator.

This regulator hinges on the fact that SC regulators are good atdividing voltages across predetermined fractional values and that buckregulators are good at regulating across a wide range of output voltagesin fine steps. For example, in a 12V-to-1V step-down regulator, the SCregulator 222 can receive 12V at V_(IN) 104 and provide a ⅙ step-down,thereby providing 2V at V_(TMP) 224. Subsequently, the buck regulator100 can provide a subsequent regulation to regulate 2V to 1V. Since thisregulator reduces the voltage swing at V_(X) 202 to V_(TMP) 224, whichcan be substantially less than V_(IN) 104, this regulator can reduce thecapacitive power loss due to the parasitic capacitance at the junction122. However, this regulator can still suffer from resistive power loss(I_(L,RMS) ²R loss) since the full amount of current required by theload 206 has to flow through the inductor 208. To reduce the resistiveloss incurred by the current, the inductor needs to have a lowresistance, which can be hard to achieve in a small die area (e.g., asmall footprint).

The present disclosure shows a hybrid regulator topology that can bemore easily integrated and that can maintain high efficiency across awide output and input voltage range, even with a small inductor. Thehybrid regulator topology can include two types of regulators: a flyingswitched-inductor regulator and a step-down regulator. A flyingswitched-inductor regulator can include a plurality of switches and aninductor that are arranged to change a voltage level of a source voltageto a target voltage; a step-down regulator can include a plurality ofswitches and a plurality of capacitors that are configured to divide avoltage level of a source voltage into an M/N fraction of the sourcevoltage. The disclosed embodiments of the hybrid regulator topology canreduce the capacitive loss (CV²f loss) of the flying switched-inductorregulator by limiting the voltage swing across the switches in theflying switched-inductor regulator. The disclosed embodiments of thehybrid regulator topology can also reduce the inductor resistive loss ofthe flying switched-inductor regulator by operating the flyingswitched-inductor regulator at a high switching frequency and with asmall amount of current flow through the inductor. This approach canreduce the resistive loss of the flying switched-inductor regulator evenwith a small inductor with a low inductance.

In some embodiments, the disclosed embodiments of the hybrid regulatortopology can be configured in a step-down configuration: a configurationin which an input voltage of the hybrid regulator is higher than anoutput voltage of the hybrid regulator. In other embodiments, thedisclosed embodiments of the hybrid regulator topology can be configuredin a step-up configuration: a configuration in which an input voltage ofthe hybrid regulator is lower than an output voltage of the hybridregulator.

In some embodiments, the hybrid regulator can be bi-directional. In abi-directional hybrid regulator, an input voltage and an output voltageof the hybrid regulator can be swapped (or flipped) to operate astep-down hybrid regulator in a step-up manner or to operate a step-uphybrid regulator in a step-down manner. For example, the input voltagecan be provided to an output terminal of the hybrid regulator and theoutput voltage can be tapped from the input terminal of the hybridregulator. This way, a step-down hybrid regulator can be operated in astep-up manner, or a step-up hybrid regulator can be operated in astep-down manner.

FIG. 3 illustrates a hybrid regulator topology in accordance with someembodiments. FIG. 3 includes a hybrid regulator 300 that includes aswitched-inductor regulator 314 and a step-down regulator 312. Theswitched-inductor regulator 314 receives a plurality of voltages, forexample, V_(IN) 308 and V_(BOTTOM) 310, and provides as output V_(TMP)302, which is a weighted average of two or more of the plurality ofvoltages, to the step-down regulator 312. The step-down regulator 312can subsequently step-down V_(TMP) 302 to the desired output voltage304. In some embodiments, the step-down regulator 312 can include an N:Mregulator, such as a switched capacitor regulator. The N:M regulator isconfigured to reduce the received voltage V_(TMP) to a fraction of M/N:

$\frac{M}{N}{V_{TMP}.}$Some examples of N:M include 1:1, 2:1, 3:1, 3:2, 4:1, 4:3, 5:1, 5:2,5:3, 5:4, 6:5, 7:1, 7:2, 7:3, 7:4, 7:5, 7:6, or any other suitablefraction.

In some embodiments, the switched-inductor regulator 314 and thestep-down regulator 312 can operate at the same switching frequency(e.g., frequency at which the switches in the switched-inductorregulator 314 and the step-down regulator 312 are controlled). In otherembodiments, the switched-inductor regulator 314 and the step-downregulator 312 can operate at two different switching frequencies. Theoperating frequency of the switched-inductor regulator 314 and thestep-down regulator 312 can be determined based on an input clocksignal. In some cases, the input clock signal for the switched-inductorregulator 314 and the step-down regulator 312 can be received from anexternal clock source; in other cases, the input clock signal for theswitched-inductor regulator 314 and the step-down regulator 312 can begenerated by a phase locked loop (PLL) integrated on the same chip asthe switched-inductor regulator 314 and the step-down regulator 312. Insome examples, the PLL can generate two or more clock signals withdifferent frequencies.

In some embodiments, the switched-inductor regulator 314 can include aflying switched-inductor regulator. In a regular switched-inductorregulator 314, the V_(BOTTOM) 310 is tied to a ground signal (0V).However, in a flying switched-inductor regulator, the V_(BOTTOM) 310 isset to be non-zero. For example, in a flying switched-inductorregulator, the V_(BOTTOM) 310 is set to be greater than 0V.

In some embodiments, the flying switched-inductor regulator 314 caninclude a flying buck regulator. FIG. 4 illustrates a hybrid regulatorhaving a flying buck regulator in accordance with some embodiments. Theflying buck regulator can operate between V_(IN) 308 and V_(BOTTOM) 310,and the flying buck regulator can be coupled to an N:M regulator 412.

The hybrid regulator 400 can reduce the resistive loss (I_(L,RMS) ²Rloss) through the inductor 108 of the flying buck regulator, therebyimproving the voltage conversion efficiency. Because the N:M regulatoris configured to step down an input voltage V_(TMP) 302 by

$\frac{M}{N},$V_(TMP) 302 is, for the most part, higher than V_(OUT). Assuming thatthe N:M regulator's efficiency is high, the power drawn by the outputload is roughly equivalent to the power drawn by the N:M regulator,which is in turn equal to the power provided by the flying buckregulator. Therefore, based on the well-known power equation: powerequals voltage multiplied by current (P=VI), the current I_(L) 112,provided by the flying buck regulator 314, is roughly

${\frac{M}{N}I_{LOAD}},$where I_(LOAD) 316 is the current drawn at the output load. Since M isoften smaller than N, the flying buck regulator 314 only needs toprovide a fraction of I_(LOAD) to the N:M regulator. Therefore, thisregulator topology can reduce the resistive loss (I_(L,RMS) ²R loss)through the inductor to roughly (M/N)². Furthermore, the reduction ofthe resistive loss becomes larger as the conversion ratio (M:N ratio)becomes larger. The resistive loss reduction is achieved by anobservation that power equals current multiplied by voltage (P=VI). Whena fixed amount of power is delivered, it is desirable to provide thepower with a high voltage, which allows for delivering only a smallamount of current.

The hybrid regulator 400 can also reduce the capacitive power loss (CV²floss) of the flying switched-inductor regulator 314. In particular, thecapacitive loss (CV²f loss) can be reduced by controlling V_(BOTTOM)310. For example, V_(BOTTOM) 310 can be any value between 0V and V_(IN)308. Since the capacitive loss can be reduced by reducing the voltageswing across the switches, the capacitive loss (CV²f loss) can bereduced by increasing V_(BOTTOM) 310 wherever possible.

In some embodiments, when V_(BOTTOM) 310 is significantly smaller thanV_(IN) 308, then the voltage across switches 114, 116 can be large. Toaddress the large voltage across the switches 114, 116, the switches114, 116 can be formed using transistors that can withstand a largevoltage across terminals. For example, the switches 114, 116 can beformed using thick-oxide transistors, such as thick-oxide MOSFETtransistors. In other examples, the switches 114, 116 can be formedusing Gallium Nitride (GaN) transistors, or any other suitabletransistors or combination of transistors.

In other embodiments, when V_(BOTTOM) 310 is not significantly smallerthan V_(IN) 308, the switches 114, 116 can be formed using regularthin-oxide transistors, such as thin-oxide MOSFET transistors.

In some embodiments, the flying switched-inductor regulator in thehybrid regulator 400 can also include a multi-phase flying buckregulator with two or more phases. The multi-phase flying buck regulatorcan include a plurality of parallel flying buck regulators that operatein a time-interleaved manner over a single period T. For example, a3-phase flying buck regulator can include three sets of switches andinductors that each operate 0 degrees, 120 degrees, 240 degrees out ofphase.

In some embodiments, the V_(BOTTOM) 310 provided to the flyingswitched-inductor regulator can be based on the output voltage of thestep-down regulator. FIGS. 5A-5D illustrate a hybrid regulator in whichV_(BOTTOM) 310 for the flying buck regulator is generated based on theoutput voltage of the step-down regulator in accordance with someembodiments. The hybrid regulator 500 includes a flyingswitched-inductor regulator and an N:M regulator 312. FIG. 5Aillustrates an embodiment in which the flying switched-inductorregulator includes a flying buck regulator, but the flyingswitched-inductor regulator can also include other types of flyingswitched-inductor regulators. The flying buck regulator is configured toreceive V_(IN) 308 and V_(BOTTOM) 310 and to provide V_(TMP) 302 to theN:M regulator 312. Subsequently, the N:M regulator 312 can step downV_(TMP) 302 to provide V_(OUT) 304.

In some embodiments, V_(BOTTOM) 310 can be based on the output voltageV_(OUT) 304. In particular, V_(BOTTOM) 310 can be set as V_(IN)−V_(OUT).The hybrid regulator 500 can generate the V_(BOTTOM) 310 using alevel-shifting converter 520. In some embodiments, the level-shiftingconverter 520 can include a flying capacitor (CO 522 and a plurality ofswitches 524-530.

The level-shifting converter 520 can provide V_(IN)−V_(OUT) asV_(BOTTOM) 310 by turning on two of the switches 524-530 at a time. Forexample, as illustrated in FIG. 5B, at time t0, the hybrid regulator 500can provide the flying capacitor 522 in parallel with the output load,illustrated as C_(LS) _(_) ₀ 522, by turning on switches 524, 526 andturning off switches 528, 530. This charges up the flying capacitor 522to V_(OUT) 304. At time t1, which is a predetermined time after t0, asshown in FIG. 5C, the hybrid regulator 500 can provide the flyingcapacitor 522 in parallel with the flying buck regulator, illustrated asC_(LS) _(_) ₁ 522-1, by turning off switches 524, 526 and turning onswitches 528, 530. By providing the plate with a positive charge toV_(IN) 304 and by providing the plate with a negative charge toV_(BOTTOM) 310, V_(BOTTOM) 310 can be set as V_(IN)−V_(OUT). FIG. 5Dillustrates the timing diagram of signals in the hybrid regulator ofFIG. 5A. FIG. 5D illustrates that the internal node Vx 102 swingsbetween V_(IN) 304 and V_(IN)−V_(OUT). Vx 102 is subsequently low-passfiltered by the inductor to generate V_(TMP) 302, which is furtherstepped-down by the step-down regulator 312 to generate V_(OUT) 304.

In some embodiments, the period in which the flying capacitor 522switches between two locations C_(LS) _(_) ₀ 522-0 and C_(LS) _(_) ₁522-1 can be equivalent to the period in which the switches in theflying buck regulator turns on and off. In some cases, the flyingcapacitor 522 can be switched between two locations C_(LS) _(_) ₀ 522-0and C_(LS) _(_) ₁ 522-1 synchronously with the turning on and off of theswitches in the flying buck regulator. For example, when the switch 114is turned on and the switch 116 is turned off, the flying capacitor 522can be provided at C_(LS) _(_) ₀ 522-0; when the switch 114 is turnedoff and the switch 116 is turned on, the flying capacitor 522 can beprovided at C_(LS) _(_) ₁ 522-1. In other embodiments, the period inwhich the flying capacitor 522 switches between two locations C_(LS)_(_) ₀ 522-0 and C_(LS) _(_) ₁ 522-1 can be equivalent to an integermultiple of the period in which the switches in the flying buckregulator turns on and off.

In some embodiments, the flying capacitor 522 can have a highcapacitance value. For example, the capacitance of the flying capacitor522 can be between 0.1-100 nF, or any other suitable capacitance values.A high capacitance flying capacitor 522 can prevent the voltage acrossthe flying capacitor 522 (and thus the voltage across the flying buckregulator) from changing significantly over time.

In some embodiments, the level-shifting converter of the hybridregulator 500 can include a separate buck converter. In otherembodiments, the level-shifting converter can include a multi-phaseconverter with two or more phases, where multiple flying capacitorsoperate in an interleaved manner.

In some embodiments, the input and output terminals of a flying buckregulator of a hybrid regulator can be flipped. Such a flying buckregulator can be referred to as a flipped flying buck regulator. Theflipped flying buck regulator can also be referred to as a flyingswitched-inductor regulator because it has a topology of a flying buckregulator that is flipped along a vertical axis. While this new topologyis referred to as a flying switched-inductor regulator, the powerdistribution mechanism of this flying switched-inductor regulator can besubstantially different from the regular flying buck regulator, asdiscussed below.

FIGS. 6A-6B illustrate a hybrid regulator having a flyingswitched-inductor regulator in accordance with some embodiments. Thehybrid regulator 600 can include a flying switched-inductor regulator614, which is coupled to the N:M regulator 312. The flyingswitched-inductor regulator 614 can include a flipped flying buckregulator, which includes an inductor 608 and a plurality of switches616, 618. Unlike conventional flying buck regulators, the flipped flyingbuck regulator 614 is coupled to V_(IN) 308 via the inductor 608, andprovides two voltages V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM)622 to the N:M regulator 312. Subsequently, the N:M regulator 312 canuse V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM) 622 to generatean output voltage V_(OUT) 304.

In the flying switched-inductor regulator 614, the input voltage V_(IN)308 is equivalent to the weighted average of the two voltages providedto the N:M regulator: V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM)622. This is different from previous embodiments because the flyingswitched-inductor regulator is flipped across the vertical axis of theillustration and the node that used to be the output is now coupled toV_(IN) 308, which can be a fixed voltage.

The flying switched-inductor regulator 614 can be configured so that theinput voltage V_(IN) 308 coupled to the inductor 608 is equivalent toV_(N:M TOP)D+V_(N:M) _(_) _(BOTTOM) (1−D), where D, a number between 0and 1, is the duty cycle in which V_(X) 602 is coupled to V_(N:M) _(_)_(TOP). Since V_(IN) is fixed, V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_)_(BOTTOM) 622 are configured to change depending on how long V_(X) 602stays coupled to V_(N:M) _(_) _(TOP) 620 and how long V_(X) 602 stayscoupled to V_(N:M) _(_) _(BOTTOM) 622. FIG. 6B illustrates the timingdiagram of signals in the hybrid regulator of FIG. 6A. FIG. 6Billustrates that the input voltage V_(IN) 308 coupled to the inductor608 is a fixed voltage. This fixed input voltage V_(IN) 308 is used togenerate two separate voltages, V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_)_(BOTTOM) 622, which are also fixed voltages. The internal node V_(X)602 is switched between V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_)_(BOTTOM) 622 at a duty cycle of D. The step-down regulator 312 usesV_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM) 622 as two inputs togenerate an output voltage V_(OUT) 304.

FIGS. 7A-7B show an exemplary embodiment of a hybrid regulator having aflying switched-inductor regulator in accordance with some embodiments.FIG. 7A shows a hybrid regulator 700 having a flying switched-inductorregulator 714, which includes an inductor 708. FIG. 7A also includes afirst set of switches 716 and a second set of switches 718. Each switchin the first set of switches 716 and the second set of switches 718 cancouple V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM) 622 to one ofthe input nodes of the step-down regulator 712 or ground (0V).

The step-down regulator 712 can include a plurality of N:M regulators.For example, in FIG. 7A, the step-down regulator 712 includes a 1:1regulator, a 2:1 regulator, a 3:1 regulator, a 4:1 regulator, and a 5:1regulator. In some embodiments, these N:M regulators (5:1, 4:1, 3:1,2:1, 1:1) can be implemented as a separate regulator. In otherembodiments, these N:M regulators (5:1, 4:1, 3:1, 2:1, 1:1) can beimplemented as a single reconfigurable SC regulator that shares switchesand capacitors. In yet other embodiments, two or more of these N:Mregulators can be implemented as a single reconfigurable SC regulator,and the rest of these N:M regulators can be implemented as separateregulators.

The step-down regulator 712 can include a plurality of input nodes, eachcoupled to one of the N:M regulators in the step-down regulator 712. Forexample, in FIG. 7A, the step-down regulator 712 includes 5 input nodes:V_(SC) _(_) _(5:1), V_(SC) _(_) _(4:1), V_(SC) _(_) _(3:1), V_(SC) _(_)_(2:1), V_(SC) _(_) _(1:1). The step-down regulator 712 also includes anoutput node, which provides an output voltage of one of the N:Mregulators.

The first set of switches 716 and the second set of switches 718 can beoperated in a time multiplexed manner. For example, at one point intime, none or one of the switches in the first set of switches 716 canbe turned on. Likewise, at one point in time, none or one of theswitches in the second set of switches 718 can be turned on. When one ofthe first set of switches 716 is turned on, then none of the second setof switches 718 is turned on; when none of the first set of switches 716is turned on, then one of the second set of switches 718 is turned on.As described in FIG. 7B, one switch in 718 and one switch in 716 canturn on and off to create a square wave at V_(X) 702.

In some embodiments, the duration in which V_(N:M) _(_) _(TOP) 720 andV_(N:M) _(_) _(BOTTOM) 722 is coupled to V_(X) 702 can be controlled tocontrol V_(OUT) 704. For example, suppose V_(IN) is 3.7V, which is atypical Li-Ion battery voltage; V_(N:M) _(_) _(TOP) 720 is coupled toV_(SC) _(_) _(4:1) via the second set of switches 718; V_(N:M) _(_)_(BOTTOM) 722 is coupled to V_(SC) _(_) _(3:1) via the first set ofswitches 716; and the target V_(OUT) 704 is 1V. Since V_(OUT) is 1V,V_(SC) _(_) _(4:1) is 4V V_(SC) _(_) _(3:1) is 3V. Since V_(IN) equalsV_(N:M) _(_) _(TOP)D+V_(N:M) _(_) _(BOTTOM) (1−D) and V_(IN) is 3.7V andV_(N:M) _(_) _(TOP) and V_(N:M) _(_) _(BOTTOM) are coupled to V_(SC)_(_) _(4:1) (4V) and V_(SC) _(_) _(3:1) (3V), respectively, the dutycycle of the flying switched-inductor regulator (D) should be 0.7. Inother words, the flying switched-inductor regulator can be coupled toV_(SC) _(_) _(4:1) 70% of the time and be coupled to V_(SC) _(_) _(3:1)the remaining 30% of the time. As another example, if the target voltageV_(OUT) 704 changes to 0.95V, V_(N:M) _(_) _(TOP) and V_(N:M) _(_)_(BOTTOM) can remain coupled to V_(SC) _(_) _(4:1) (3.8V) and V_(SC)_(_) _(3:1) (2.85V), respectively, but D can change to 0.89. This D isderived from the equation 3.7=3.8D+2.85 (1−D), which comes fromV_(IN)=V_(N:M) _(_) _(TOP)D+V_(N:M) _(_) _(BOTTOM) (1-D). As anotherexample, if the target voltage V_(OUT) 704 changes to 0.9V, V_(N:M) _(_)_(TOP) and V_(N:M) _(_) _(BOTTOM) can be coupled to V_(SC) _(_) _(5:1)(4.5V) and V_(SC) _(_) _(4:1) (3.6V), respectively, and D can change to0.11. FIG. 7B illustrates the timing diagram of signals in the hybridregulator. In FIG. 7B, one of the first set of switches 716 isconfigured to couple V_(SC) _(_) _(3:1) to V_(N:M) _(_) _(BOTTOM), andone of the second set of switches 718 is configured to couple V_(SC)_(_) _(4:1) to V_(N:M) _(_) _(TOP). As illustrated in FIG. 6B, V_(SC)_(_) _(3:1) and V_(SC) _(_) _(4:1) can be duty-cycled to generateV_(OUT) 704.

In some embodiments, the first set of switches 716 and the second set ofswitches 718 can be a part of the flying switched-inductor regulator. Inother embodiments, the first set of switches 716 and the second set ofswitches 718 can be a part of the step-down regulator 712. For example,the step-down regulator 712 can determine which one of the switches inthe first set of switches 716 and the second set of switches 718 can becoupled to V_(N:M) _(_) _(TOP) and V_(N:M) _(_) _(BOTTOM), and theflying switched-inductor regulator can determine the value of D (dutycycle).

The embodiment illustrated in FIG. 7A can reduce the parasiticcapacitance and parasitic resistance associated with the inductor 708.FIGS. 8A-8B illustrate how an inductor can be coupled to a hybridregulator in accordance with some embodiments. FIG. 8A illustrates howan inductor can be coupled to two or more internal nodes of the chip;FIG. 8B illustrates how an inductor can be coupled to one internal nodeof the chip. In some embodiments, the inductors can be implemented onthe same die as the voltage regulator, but on different metal layers. Inthis case, the pads 806, 808 can be implemented using vias. In someembodiments, the inductors can be implemented on a different die as thevoltage regulator or are discrete components that are placed externally.In this case, the pads, 806, 808 can be implemented as regular pads onthe voltage regulator die. In either type of embodiments, there areparasitic losses associated with the pads 806, 808 due to parasiticcapacitance and/or parasitic inductance.

In embodiments illustrated in FIGS. 3-5, the inductor is coupled to twointernal nodes of the hybrid regulator. For example, the inductor in thebuck regulator/flying buck regulator of the hybrid regulator is coupledto two internal nodes of the hybrid regulator. In this case, the outputcurrent of the buck regulator/flying buck regulator can flow out through806, through the inductor 804, and then flows back in through 808.Therefore, the hybrid regulator is affected by the parasitic losses ofboth pads 806, 808.

In contrast, in embodiments illustrated in FIGS. 6-7, the inductor iscoupled to only one internal node of the hybrid regulator. For example,the inductor in the flying switched-inductor regulator is coupled toV_(IN) 814 and an internal node of the hybrid regulator. In this case,the current of the flying switched-inductor regulator can flow throughthe inductor 812 and flows into the voltage regulator die through 816.Therefore, the current flows through only one of the pads 806, 808,which can reduce the parasitic loss.

In embodiments illustrated in FIGS. 3-7, all N:M regulators can includea flying switched-inductor or switched-capacitor or a hybrid of the two,comprising one or more switches connecting/disconnecting one or morecapacitors or one or more inductors. The N:M regulators can also bereconfigurable regulator structures that dynamically change to differentconversion ratios (e.g., (N−1):M (N−2):M, N:(M−1), N:(M−2), (N−1):(M−1),etc.). A typical inductance of the inductor in the flyingswitched-inductor regulator can range from 100 pico-Henry to 1micro-Henry and power switches in the flying switched-inductor regulatorcan typically have width/(minimum length) values of 1000 to 100,000. Forexample, in a 90 nm process technology, power switch widths typicallyrange from 100 um to 10 mm. Switching frequencies typically range from10 MHz to 500 MHz.

As illustrated above, the N:M regulator can be implemented using a SCregulator. In some cases, the SC regulator may not be able to step downthe input voltage V_(TMP) to

$\frac{M}{N}{V_{TMP}.}$Instead, the SC regulator can provide, as V_(OUT),

${{\frac{M}{N}V_{TMP}} - V_{DELTA}},$where V_(DELTA) is a small value. For example, in 90 nm processes,V_(DELTA) is in the range of 0-200 mV. In some cases, V_(DELTA) canexist because of the non-ideal characteristics of the SC regulator. Forexample, the non-ideal characteristics can include the parasiticcapacitance. However, oftentimes V_(DELTA) is can be substantially smallcompared to the output voltage. In some cases, the efficiency of the SCregulator can be the highest when

$V_{OUT} = {{\frac{M}{N}V_{TMP}} - {V_{DELTA}.}}$

In some embodiments, the hybrid regulators disclosed in FIGS. 3-7 can becontrolled using a feedback system. The feedback system can determine,in substantially real time, whether the output voltage of the hybridregulator is within the tolerable error range from the target outputvoltage.

In some embodiments, the feedback system can include a plurality offeedback systems. FIG. 9 illustrates a hybrid regulator with a pluralityof feedback systems in accordance with some embodiments. FIG. 9 includesthe two-stage hybrid regulator as described in FIG. 3. FIG. 9 furtherincludes a first feedback loop 928 and a second feedback loop 930. Thefirst feedback loop 928 is configured to control the step-down regulator312, and the second feedback loop 930 is configured to control theflying switched-inductor regulator 314.

The first feedback loop 928 and the second feedback loop 930 areconfigured to cooperate with one another so that the step-down regulator312 can operate close to its high efficiency range. As discussed above,the efficiency of the SC regulator can be the highest when the outputvoltage V_(OUT) is close to

${\frac{M}{N}V_{TMP}} - {V_{DELTA}.}$Therefore, the first feedback loop 928 is configured to operate thestep-down regulator 312 so that the output voltage V_(OUT) is close to

${\frac{M}{N}V_{TMP}} - {V_{DELTA}.}$At the same time, the second feedback loop 930 is configured to operatethe flying switched-inductor regulator 314 so that the output voltageV_(OUT) is close to the target voltage.

In some sense, the first feedback loop 928 is a slow loop that operatesthe SC regulator to operate at a high efficiency and the second feedbackloop 930 is a fast loop that reacts quickly to load fluctuations so thatV_(OUT) stays close to V_(REF). The digital blocks 908 920 can besynthesized using hardware programming languages including Verilog, VHDLand Bluespec.

For example, suppose V_(IN)=3.7V; the target V_(OUT) is 1V (V_(REF)equals 1V); and the step-down regulator 312 is a 3:1 SC regulator. Inthis case, the SC regulator has a high efficiency when V_(TMP)/V_(OUT)is close to 3. However, V_(TMP)/V_(OUT) can be equal to 3 only in idealconditions, and in non-ideal conditions, there is a small voltage dropV_(DELTA) in V_(OUT) voltage. As a result, the SC regulator has a highefficiency when V_(OUT) is close to V_(TMP)/3−V_(DELTA).

To increase the efficiency of the step-down regulator 312, the firstfeedback system 928 can control the step-down regulator 312 to provide,as output voltage V_(OUT) 304, a voltage close to V_(TMP)/3−V_(DELTA).To this end, the first feedback system 928 can use a comparator 910 thatcompares V_(TMP)/3−V_(DELTA) and V_(OUT) and sends the comparison resultto a digital block 908. The comparison result can include a binarysignal, indicating whether V_(OUT) is greater than V_(TMP)/3−V_(DELTA)or not. Subsequently, the digital block 908 of the first feedback system928 can generate a signal 906 that controls the power switches of the SCregulator 914 so that V_(OUT) is within a tolerable error range fromV_(TMP)/3−V_(DELTA).

In some embodiments, the second feedback loop 930 can use theinformation about the step-down regulator 312 to control the flyingswitched-inductor regulator 314. For example, assuming that V_(DELTA) is0.1V, V_(TMP) can be 3.3V so that V_(OUT) is close to the target valueof 1V. Thus, the second feedback system 930 can set V_(TMP) to 3.3V.

The second feedback system 928 can set V_(TMP) as 3.3V using acomparator 926. The comparator 926 can compare V_(REF) (1V) and V_(OUT)and send a comparison result to the digital block 920. Subsequently, thedigital block 920 can control the duty cycle of the flyingswitched-inductor regulator 314 so that V_(OUT) is close to the desiredvalue, in this case 1V. This feedback mechanism can automatically setV_(TMP) close to 3.3V.

Using these two loops, the step-down regulator can operate at highefficiency by setting V_(OUT) close to V_(TMP)/3−V_(DELTA) and theflying switched-inductor regulator 314 can set its duty cycle togenerate the appropriate V_(TMP) so that V_(OUT) is close to the targetvalue.

FIG. 10 illustrates a hybrid regulator with a plurality of feedbacksystems having a different configuration in accordance with someembodiments. FIG. 10 includes a first feedback loop 1028 and a secondfeedback loop 1030. The first feedback loop 1028 is configured tocontrol the step-down regulator 312, and the second feedback loop 1030is configured to control the flying switched-inductor regulator 314.

The embodiment illustrated in FIG. 10 is substantially similar to theembodiment in FIG. 9. The difference is that the first feedback loop1028 is a fast loop that reacts quickly to load fluctuations so thatV_(OUT) stays close to V_(REF), whereas the second feedback loop 1030 aslow loop that operates the SC regulator to operate at a highefficiency.

In some embodiments, the digital blocks 908, 920, 1008, 1020 can besynthesized using hardware programming languages. The hardwareprogramming languages can include Verilog, VHDL, Bluespec, or any othersuitable hardware programming language. In other embodiments, thedigital blocks 908, 920, 1008, 1020 can be manually designed and can bemanually laid-out on a chip.

The hybrid regulator can use a feedback system in accordance with theembodiment of FIG. 9 or FIG. 10, depending on the maximum controlbandwidth limited by their respective switching frequencies. When themaximum control bandwidth of the flying switched-inductor regulator 314is higher than that of the step-down regulator 312, the feedback systemin accordance with the embodiment of FIG. 9 can allow the hybridregulator to have a higher loop bandwidth, thereby allowing the hybridregulator to respond quickly to any fluctuations in the output voltage304. When the maximum control bandwidth of the step-down regulator 312is higher than that of the flying switched-inductor regulator 314, thefeedback system of FIG. 10 allows the full system to have a higher loopbandwidth.

In some embodiment, the hybrid regulator can include a dead-zonefeedback system that can address dead-zones of the flyingswitched-inductor regulator. For the sake of simplicity, the dead-zonefeedback system is illustrated with respect to the hybrid regulator ofFIG. 5, but this dead-zone feedback system can be used for any of thedisclosed hybrid regulators.

A dead-zone of a flying switched-inductor regulator refers to a range ofvoltages that cannot be generated by the flying switched-inductorregulator. For example, in FIG. 5, the flying switched-inductorregulator should be able to generate all voltages between V_(IN) 308 andV_(BOTTOM) 310 by varying the duty cycle D between 0 and 1. However, dueto efficiency reasons, the duty cycle D is often limited to 0.05 and0.95. Thus, voltages between V_(BOTTOM) and V_(BOTTOM)+0.05(V_(IN)−V_(BOTTOM)), and voltages V_(BOTTOM)+0.95 (V_(IN)−V_(BOTTOM))and V_(IN) cannot be generated.

This dead-zone can potentially have an impact in the performance of thehybrid regulator because with the dead-zone, the hybrid regulator maynot be able to generate all desired voltages within the range ofinterest. This issue is described below with an example.

Suppose V_(IN) is 3.7V, which is a typical Li-Ion battery voltage; thetarget V_(OUT) 504 is 1.15V; and the step-down regulator is a 3:1 SCregulator. Assuming the duty cycle of the flying switched-inductorregulator is D,V_(TMP)=V_(IN)D+(V_(IN)−V_(OUT))(1−D)=V_(IN)−V_(OUT)(1−D). A 3:1 SCregulator may not have a conversion ratio that is exactly 3:1, butinstead can have a slightly higher conversion ratio due to a slightvoltage drop on V_(OUT). Therefore, the conversion ratio of a 3:1 SCregulator is 3+N_(DELTA), where N_(DELTA) is a number around 0.1. SinceV_(TMP)=(3+N_(DELTA))V_(OUT), combining with the equation above,V_(IN)−V_(OUT)(1−D)=(3+N_(DELTA))V_(OUT), which leads toV_(IN)=(4−D+N_(DELTA))V_(OUT), or V_(IN)/(4−D+N_(DELTA))=V_(OUT). SinceD is a number between 0 and 1, this regulator can set V_(OUT) to valuesbetween V_(IN)/(4+N_(DELTA)) when D=0 and V_(IN)/(3+N_(DELTA)) when D=1.If the step-down regulator is, instead, a 4:1 SC regulator, thisequation becomes V_(IN)/(5−D+N_(DELTA))=V_(OUT), and regulator can setV_(OUT) to values between V_(IN)/(5+N_(DELTA)) when D=0 andV_(IN)/(4+N_(DELTA)) when D=1.

As described in FIG. 11, by changing the conversion ratio of thestep-down regulator and the duty cycle of the flying switched-inductorregulator, this regulator can set V_(OUT) to a wide range of voltages.However, in non-ideal cases, the flying switched-inductor regulator'sduty cycle cannot be very high or very low, so a more realistic rangewould be something close to 0.05 to 0.95, instead of 0 to 1, asdescribed in FIG. 12. Since the flying switched-inductor regulator'sduty cycle has a dead-zone from 0 to 0.05, and from 0.95 to 1, there aresome values to which V_(OUT) cannot be set.

To overcome this problem, when it is desirable to operate the flyingswitched-inductor regulator 312 in the dead-zones, the step-downregulator 314 can perform the regulation by adjusting N_(DELTA). Forexample, when the 2^(nd) stage is a 4:1 SC regulator, the regulator canset V_(OUT) to values between V_(IN)/4.95 (D=0.05) and V_(IN)/4.05(D=0.95). To set V_(OUT) to values from V_(IN)/5 to V_(IN)/4.95,N_(DELTA) can be somewhere between 0 and 0.05. To set V_(OUT) to valuesfrom V_(IN)/4.05 to V_(IN)/4, the SC regulator should change to a 3:1conversion ratio and set N_(DELTA) to be somewhere between 0.05 and 0.1.

In some embodiments, the step-down regulator 314 can modify N_(DELTA) bycontrolling the amount of voltage drop for the output voltage V_(OUT)304. The step-down regulator 314 can control the amount of voltage dropfor the output voltage V_(OUT) 304 using a programmable electricalcomponent. In some embodiments, the programmable electrical componentcan include a programmable resistor bank. The step-down regulator 314can provide a programmable resistor bank at the output node of thestep-down regulator and control the resistance of the programmableresistor bank to control N_(DELTA). One or more resistors in theresistor bank can be implemented using physical resistors, made frommetal, poly-silicon or silicon layers. The silicon layers can include anN-type diffusion layer or a P-type diffusion layer. One or moreresistors in the resistor bank can be implemented using transistorssince they have a controllable resistance between source and drainterminals.

In other embodiments, the programmable electrical component forcontrolling the amount of voltage drop for the output voltage V_(OUT)304 can include a current source and a transistor. The current sourcecan be configured to provide a predetermined amount of current to thetransistor so that a predetermined voltage drop can be induced acrossthe transistor.

In some embodiments, the current source in the programmable electricalcomponent can be programmable. In some cases, the programmable currentsource can be implemented using a plurality of current source units. Theprogrammable current source can be programmed to provide a predeterminedamount of current by turning on a desired number of current sourceswhile leaving the rest of them off. In some cases, a current source canbe implemented using a transistor. For example, the gate voltage of thetransistor can be controlled to adjust the amount of current flowingthrough the source and drain terminals. In some embodiments, theprogrammable current source can be implemented using a digital to analogconverter (DAC).

In some embodiments, the transistor in the programmable electricalcomponent can also be programmable. In particular, the transistor can beprogrammed to provide a desirable width and/or length. Such transistorcan be referred to as a programmable transistor. The programmabletransistor can be implemented using a plurality of transistor unitshaving a predetermined width and/or length. For example, theprogrammable transistors can include a plurality of transistor unitsdisposed in a parallel manner. The width and/or length of theprogrammable transistor can be controlled by turning on a desirablenumber of the transistor units while leaving the rest of them off.

In some embodiments, the hybrid converter can operate in a step-downconfiguration. For example, as illustrated in FIG. 3, the output voltageof the hybrid converter can be lower than the input voltage of thehybrid converter. In other embodiments, the hybrid converter can operatein a step-up configuration. The step-up configuration of the hybridconverter can be realized simply by swapping or flipping the outputterminal and the input terminal of the hybrid converter.

FIG. 13 illustrates a hybrid converter in a step-up configuration inaccordance with some embodiments. The operation of the hybrid converter1300 in a step-up configuration is similar to the operation of thehybrid converter 300 in a step-down configuration in FIG. 3, except thatthe location of V_(IN) 308 and V_(OUT) 304 are swapped and V_(IN) 1302is lower than V_(OUT) 1310.

For example, the hybrid converter 1300 is configured to receive an inputvoltage V_(IN) 1302 at an output node of the step-down regulator 312.Because the input node and the output node of the step-down regulator312 has been flipped in this configuration, the step-down regulator 312is in effect operating as a step-up regulator. Therefore, the step-downregulator 312 is configured to provide a stepped-up voltage signalV_(TMP) 1304 and a current I_(L) 1306. The flying switched-inductorregulator 314 can receive, at its output, the stepped-up voltage signalV_(TMP) 1304 and the current I_(L) 1306, and provide a stepped-up outputvoltage V_(OUT) 1310, as a function of the bottom voltage V_(BOTTOM)1308, and the output current I_(LOAD) 1312.

FIGS. 14A-14B illustrate an operation of a hybrid converter in a step-upconfiguration in accordance with some embodiments. FIG. 14A illustratesa scenario in which the flying switched-inductor regulator 314 in thehybrid regulator 1400 is a flying buck regulator. In this case, theintermediate voltage V_(X) 1402 alternates between the output voltageV_(OUT) 1310 and the bottom voltage V_(BOTTOM) 1308, depending on whichone of the switches 114, 116 is turned on. In some embodiments, thecontrol signals for controlling the components in FIG. 14A can besubstantially similar to the control signals for controlling thecomponents in FIG. 4. As illustrated in the timing diagram 1404 of FIG.14B, because the hybrid converter is in a step-up configuration, theoutput voltage V_(OUT) 1310 is higher than the input voltage V_(IN)1302.

In some embodiments, the hybrid converters 1300, 1400 can be used inconjunction with a level shifting regulator in a manner substantiallysimilar to how the hybrid converters 300, 400 can be used in conjunctionwith the level shifting regulator 520, as illustrated in FIGS. 5A-5C. Insome embodiments, the hybrid converters 1300, 1400 can be used inconjunction with one or more feedback control loops in a mannersubstantially similar to how the hybrid converters 300, 400 can be usedin conjunction with one or more feedback control loops 928, 930, 1028,1030, as illustrated in FIGS. 9-10. In some cases, the one or morefeedback control loops can also implement the dead-zone aware controlmechanism, as illustrated in conjunction with FIGS. 11-12.

In some embodiments, a hybrid converter including a flyingswitched-inductor regulator can also be configured in a step-upconfiguration. FIGS. 15A-15B illustrate a hybrid converter including aflying switched-inductor regulator in a step-up configuration inaccordance with some embodiments. The operation of the hybrid converter1500 in a step-up configuration is similar to the operation of thehybrid converter 500 in a step-down configuration in FIG. 5, except thatthe location of V_(IN) 1502 and V_(OUT) 1516 are swapped and V_(IN) 1502is lower than V_(OUT) 1516.

For example, the hybrid converter 1500 is configured to receive an inputvoltage V_(IN) 1502 at an output node of the step-down regulator 312.Because the input node and the output node of the step-down regulator312 has been flipped in this configuration, the step-down regulator 312is in effect operating as a step-up regulator. When the step-downregulator 312 has multiple input voltage terminals, each terminal isconfigured to receive a voltage signal that is stepped down by adifferent ratio, and the step-down regulator 312 is configured toprovide two or more stepped-up voltage signals V_(N:M) _(_) _(TOP) 1508and V_(N:M) _(_) _(BOTTOM) 1510.

The two or more stepped-up voltage signals 1508, 1510 can be provided totwo or more switches 615, 618 in the flying switched-inductor regulator614 so that the two or more switches 615, 618 can provide one of the twoor more stepped-up voltage signals 1508, 1510 to an inductor 608 in atime-multiplexed manner. This generates an intermediate voltage V_(X)1512 and a load current I_(L) 1514 at a first node of the inductor 608.The inductor can smooth out the intermediate voltage V_(X) 1512 toprovide an output voltage V_(OUT) 1516 and an output current I_(OUT)1518. FIG. 15B shows a timing diagram of the two or more stepped-upvoltage signals 1508, 1510, the intermediate voltage V_(X) 1512, and theoutput voltage V_(OUT) 1516.

FIGS. 16A-16B illustrate an operation of a hybrid regulator having aflying switched-inductor regulator in accordance with some embodiments.FIG. 16A illustrates a scenario in the hybrid regulator 1500 includes aflying switched-inductor regulator 714 having an inductor 608. In thiscase, the control signals for controlling the components in FIG. 16A canbe substantially similar to the control signals for controlling thecomponents in FIG. 7. As illustrated in the timing diagram 1602 of FIG.16B, because the hybrid converter 1500 is in a step-up configuration,the output voltage V_(OUT) 1516 is higher than the input voltage V_(IN)1502.

In some embodiments, the hybrid converters 1300, 1400, 1500, 1600 in astep-up configuration can be used in various applications. In a mobilehandheld device, the input voltage 1302, 1502 can be a Lithium-Ion(Li-Ion) battery providing a voltage signal within a 2.8-4.3V voltagerange, and the load I_(LOAD) 706 can be used to drive one or more of adisplay backlight, a camera flash, and one or more Organic LightEmitting Diode (OLED) displays. Some of these loads may use a voltagethat is higher than the Li-Ion battery voltage. Therefore, the hybridconverters 1300, 1400, 1500, 1600 in a step-up configuration can beuseful in providing voltage and current signals for some of these loads.

In some embodiments, a hybrid converter can be configured in a step-downor a step-up configuration without having to flip the input voltageterminal and an output voltage terminal. FIG. 17 shows a hybridconverter that can provide both step-down and step-up voltage regulationin accordance with some embodiments. The hybrid converter 1700 issimilar to the hybrid converter 600. The difference between the hybridconverter 1700 and the hybrid converter 600 is that the hybrid converter1700 includes a step-down/up converter 1702 that is capable of providingboth step-up and step-down regulation of voltage signals. Thestep-down/up converter 1702 can include a plurality of output terminalsthat can each provide an output voltage signal that is lower or higherthan V_(IN) 308. The switch matrix 1704 coupled to the step-down/upconverter 1702 can operate as a multiplexer that is configured to selectone of the plurality of output terminals to be coupled to the load ofthe hybrid converter 1700, thereby providing the final output voltage,V_(OUT) 304. Therefore, the final output voltage V_(OUT) 304 can belower (step-down) or higher (step-up) than the input voltage V_(IN) 308,depending on the configuration of the switches 1704.

In some embodiments, the step-down/up converter 1702 can include one ormore switched capacitor regulators that are configured to provide adistinct voltage gain setting. The one or more switched capacitorregulators can be configured to provide a predetermined increase (orgain) or a predetermined decrease (or reduction) of voltage in a voltagesignal received by the one or more switched capacitor regulators.Therefore, the step-down/up converter 1702 can be configured toaccommodate one or more distinct voltage gain settings.

In some embodiments, input terminals of the one or more switchedcapacitor regulators in the step-down/up converter 1702 can be coupledto the inductor 608 using a dedicated set of switches. For example,input terminals of the one or more switched capacitor regulators in thestep-down/up converter 1702 can be coupled to the inductor 608 using aplurality of switches 716, 718 as illustrated in FIG. 7A.

In some embodiments, the hybrid converter 1700 can be used inconjunction with a level shifting regulator in a manner substantiallysimilar to how the hybrid converters 300, 400 can be used in conjunctionwith the level shifting regulator 520, as illustrated in FIGS. 5A-5C. Insome embodiments, the hybrid converter 1700 can be used in conjunctionwith one or more feedback control loops in a manner substantiallysimilar to how the hybrid converters 300, 400 can be used in conjunctionwith one or more feedback control loops 928, 930, 1028, 1030, asillustrated in FIGS. 9-10. In some cases, the one or more feedbackcontrol loops can also implement the dead-zone aware control mechanism,as illustrated in conjunction with FIGS. 11-12.

In some embodiments, the hybrid converter 1700 can be operated in areverse configuration (e.g., the input terminal and the output terminalof the hybrid converter 1700 are switched.) The operational direction ofthe hybrid converter 1700 can be flexibly modified to accommodatevarious types of input voltage sources and output loads coupled to theinput terminal and the output terminal of the hybrid converter 1700.

Various embodiments of the disclosed hybrid converters can be used as abattery charger in a battery-operated device. For example, an outputnode of a hybrid converter can be coupled to a battery so that theoutput voltage and the output current of the hybrid converter are usedto charge the battery. The hybrid converter can be particularly usefulin charging batteries in a handheld device. A handheld device, such as asmartphone, can use a Lithium-Ion (Li-Ion) battery that is configured toprovide a voltage output within the range of approximately 2.8-4.3V,depending on whether the battery is charged or not (e.g., 4.3V whenfully charged, 2.8V when fully discharged). The Li Ion battery in thehandheld device can be charged using a Universal Serial Bus (USB). Thecurrent version of the USB power line uses 5V (and the future versionsof the USB may use even higher voltages), which is higher than thevoltage output of the Li Ion battery. Therefore, the voltage from theUSB power line should be stepped down before it can be used to chargethe Li Ion battery. To this end, the hybrid converter can be configuredto receive the power line voltage and current from the USB and provide astep-down version of the power line voltage and current to the Li-Ionbattery so that the Li-Ion battery can be charged based on the voltageand current from the USB.

In some embodiments, the above-identified configuration, in which abattery is charged using a USB power line, can be used in reverse as aUSB On-The-Go (OTG), where the battery in a first device can deliverpower to a second device over USB to charge the second device. In thisscenario, a battery in a first device is configured to deliver currentto a battery in a second device through a USB. Although the outputvoltage of the battery in the first device may be lower than the USBpower line voltage, the hybrid converter can operate in a step-upconfiguration to step-up the output voltage of the battery to that ofthe USB power line. This way, the battery in the first device can chargethe battery in the second device over the USB power line.

In some cases, a hybrid regulator can achieve a high performance interms of, for example, the power conversion efficiency, the powerdensity, and the control loop bandwidth, by using appropriatefabrication processes and integration methods.

In some embodiments, an appropriate fabrication process technology canimprove the quality of passive components in the hybrid regulator. Inparticular, an appropriate fabrication process technology can increasethe capacitance density of capacitors and also reduce the parasiticcapacitance of capacitors in the hybrid regulator. Also, an appropriatefabrication process technology can allow for a fabrication of aninductor using thick metals with very low parasitic resistance. Bothhigh capacitance density capacitors and low resistance inductors canimprove the power density (e.g., the power transfer capability) andpower transfer efficiency of IVRs.

In some embodiments, one or more blocks of a hybrid regulator can beimplemented in a DRAM process that allows for a fabrication ofhigh-density capacitors that are often used in DRAM cells. A hybridregulator can also utilize ultra-thick metals, having a thickness in therange of about 3-10 μm, with low sheet resistance to implementhigh-quality, on-chip spiral inductors.

In some cases, the performance of a hybrid regulator can depend on howit is integrated with other chips or systems. For example, theimplementation of passive components, including inductors andcapacitors, and power distribution network (e.g., power grid) can besubject to a trade-off between the quality of the passive components(e.g., capacitance density of capacitors and the parasitic resistance ofinductors) and the size of the IVR chip, the circuit board embodying theIVR chip, and/or the electronic system embodying the IVR chip. Forexample, the full integration of passive components can allow for an IVRsystem having a small form factor (e.g., a small size), but at the costof lower quality passive components compared with the passive componentsin an on-package IVR system or the passive components embodied as anoff-chip component.

In some embodiment, a hybrid regulator can be implemented as anintegrated regulator in which all components are integrated on a singledie. FIG. 18 illustrates an integrated regulator in accordance with someembodiments. The die 1800 can include switches, feedback controlcircuitries, and capacitors in the upper metal layers of the die 1800,including the front-end-of-line (FEOL) layers and thin metal layers,while the die 1800 can include one or more inductors in the lower metallayers that can accommodate thicker metals. The FEOL layers include oneof the bottom layers in an integrated-chip (IC) where the individualactive and passive devices (transistors, capacitors, resistors, etc.)are patterned. FIG. 18 illustrates a flip-chip packaging implementationin which the die 1800 is flipped for a flip-chip package. However, thedie 1800 can be packaged in an up-right package as well. The die 1800can be coupled to the printed circuit board (PCB) via solders 1804. Theupper layers can be coupled to the lower layers through a set ofinterconnects such as vias and metals.

In some embodiment, a hybrid regulator can be implemented as anintegrated regulator in which all components are integrated on a singledie, but in a different configuration compared to FIG. 18. FIG. 19illustrates an integrated regulator in accordance with some embodiments.The die 1900 can include switches and feedback control circuitries inthe upper metal layers, including the front end of line layers and thinmetal layers, while the die 1900 can include capacitors and inductors inthe lower metal layers with thicker metals and materials necessary fordenser capacitors. The upper layers can be coupled to the lower layersthrough a set of interconnects such as vias and metals.

In some embodiment, portions of a hybrid regulator can be implemented ona single die while one or more inductors are implemented as discretecomponents, as illustrated in FIG. 20 in accordance with someembodiments. For example, the die 2000 includes power switches, feedbackcontrol circuitries and capacitors in the upper layers, while inductors2002 are implemented as discrete components. The inductor can include a0201, 0402, 0308, 0805 discrete inductor.

In some embodiment, portions of a hybrid regulator can be implemented ona single die while one or more inductors are implemented as discretecomponents, as illustrated in FIG. 21 in accordance with someembodiments. The die 2100 includes switches and feedback controlcircuitries in the upper layers, including the front end of line layersand thin metal layers, while the die 2100 includes capacitors in thelower layers with materials necessary for denser capacitors. The upperlayers can be coupled to the lower layers through a set of interconnectssuch as vias and metals.

In some embodiments, as illustrated in FIG. 22, one or more integratedvoltage regulator dies 2200, including power switches, feedback controlcircuitries, capacitors and inductors, can be placed side-by-side nextto another system-on-chip (SoC) die 2202 on an SoC package substrate2204.

In some embodiments, as illustrated in FIG. 23, one or more integratedvoltage regulator dies 2300, including power switches, feedback controlcircuitries, capacitors, can be placed side-by-side next to another SoCdie 2202 on an SoC package substrate 2204, along with discrete inductorcomponents 2002. The inductors 2002 can include 0201, 0402, 0308, 0805discrete inductors.

In some embodiments, as illustrated in FIG. 24, one or more integratedvoltage regulator dies or packages 2400, including power switches,feedback control circuitries, capacitors and inductors, are placedside-by-side next to another SoC 2402 on a PCB 1802.

In some embodiments, as illustrated in FIG. 25, one or more integratedvoltage regulator dies or packages 2500 containing power switches,feedback control circuitries, capacitors are placed side-by-side next toanother SoC 2402 on a PCB 1802 along with discrete inductor 2002components. The inductors 2002 can be 0201, 0402, 0308, 0805 discreteinductors.

In some embodiments, as illustrated in FIG. 26, few, large IVR dies 2600can be placed next to another SoC die 2202 in an SoC package 2204.

In some embodiments, as illustrated in FIG. 27, large number of small“integrated voltage regulator” dies 2700 surround another SoC die 2202in an SoC package 2204.

In some embodiments, a die, illustrated in FIGS. 18-27, can be packagedin a through-hole package. The through-hole package can include a singlein-line package, a dual in-line package (DIP), a ceramic DIP, a glasssealed ceramic DIP, a quadruple in-line package, a skinny DIP, a zig-zagin-line package, a molded DIP, or a plastic DIP. In some embodiments,the die can be packaged as a surface mount. The surface mount caninclude a ceramic column grid array (CGA), a column grid array, aceramic package, a land grid array (LGA), and a multi-chip module (MCM).In some embodiments, the die can be packaged in a chip carrier. A chipcarrier can include a rectangular package with electric contacts on allfour edges of the package. The chip carrier can include a bump chipcarrier (BCC), a ceramic leadless chip carrier (CLCC), a dual lead-lesschip carrier (DLCC), and a plastic leaded chip carrier (PLCC). In someembodiments, the die can be packaged in using pin grid arrays. The pingrid arrays can include an organic pin grid array (OPGA), a flip-chippin grid array (FCPGA), a pin array cartridge (PAC), a pin grid array(PGA), and a ceramic pin grid array (CPGA). In some embodiments, the diecan be packaged in using ball grid arrays. A ball grid array can includea fine pitch ball grid array (FBGA), a ceramic ball grid array (CBGA), aplastic ball grid array (PBGA), and a thin ball grid array (TBGA).

When a hybrid regulator is initially powered up, the signals in thehybrid regulator are ramped to a stable state. The transient statebetween the off state, when all inputs and outputs are grounded, and theon state, when the input voltage and output voltage have all reachedtheir respective stable states, is referred to as a start-up. In someembodiments, the input voltage from the power source, such as a battery,and the regulated output voltage of the hybrid regulator can start-uptogether (or ramp up together). In other words, in those embodiments,the input voltage from the power source can be controlled so that it isramped up together with the regulated output voltage. To this end, thehybrid regulator can use a simple start-up circuitry to allow for asmooth start-up. In particular, the start-up circuitry can maintain aconstant ratio of input voltage and the output voltage so that the inputpower source can smoothly charge up the output voltage, without causingany sudden voltage instabilities.

In other embodiments, the input power source may not be controlled.Instead, the input power source can constantly provide a fixed,predetermined voltage even when the hybrid regulator is off. Forexample, in the particular implementation of the hybrid regulator inFIG. 6, the output V_(OUT) 304 can ramp up from 0V to a stable outputvoltage while the input V_(IN) 308 is fixed at a predetermined inputvoltage. In this situation, as the output V_(OUT) 304 ramps up from 0V,so are the voltages at V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_)_(BOTTOM) 622. This causes a big voltage differential across theinductor 608, which can cause a large current I_(L) 312 through theinductor until V_(N:M) _(_) _(TOP) 620 rises above V_(IN) 308. Thislarge current I_(L) 312 is often referred to as an inrush current. Thisbig, sudden current draw can damage the inductor 608 and/or othercomponents in the hybrid regulator.

In some embodiments, a flying switched-inductor regulator in a hybridregulator can include a shunt switch. FIG. 28 illustrates a hybridregulator having a flying switched-inductor regulator with a shuntswitch in accordance with some embodiments. FIG. 28 includes a hybridregulator of FIG. 6, and also a shunt switch 2802. The shunt transistor2802 can provide a soft startup mechanism for the inductor 608 andsuppress inrush current in the inductor 608 during start-up. Each nodeof the shunt switch 2802 can be coupled different node of the inductor608, thereby coupling the input voltage V_(IN) 308 and the intermediatenode V_(X) 602. During start-up, the shunt switch 630 is turned on,thereby shorting the two terminals of the inductor 608. This can ensurethat no current is built up in inductor 608 during start-up and that theintermediate node V_(X) 602 is at the same potential as the inputvoltage V_(IN) 308. During the start-up process, while the shunt switch630 is on, one or more of the switches 616, 618 can be turned on and offso that the input voltage V_(IN) 308 can charge up V_(N:M) _(_) _(TOP)620 and/or V_(N:M) _(_) _(BOTTOM) 622 via the switches 616, 618. In someembodiments, the one or more of the switches 616, 618 can be turned onand off in accordance with a predetermined programmable duty cycle sothat V_(N:M) _(_) _(TOP) 620 and/or V_(N:M) _(_) _(BOTTOM) 622 can rampup slowly. In some embodiments, the predetermined duty cycle of theswitches 616, 618 can be increased over time from zero to a particularvalue to slowly raise V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM)622 and thus V_(OUT) 304. These features can enable a smooth start-up ofthe hybrid regulator.

In some embodiments, the inductor-switched regulator can include aseries switch and a shunt switch. FIG. 29 illustrates a hybrid regulatorhaving a flying switched-inductor regulator with a series switch and ashunt switch in accordance with some embodiments. FIG. 29 includes ahybrid regulator of FIG. 6, and also a series switch 2902 and a shuntswitch 2802. During start-up, the series switch 2902 is turned OFF inorder to isolate the inductor 608 from the start-up operation. This canensure that the current I_(L) 612 through the inductor stays at zerountil the start-up process is completed.

Because the current I_(L) 612 is zero during the start-up process,V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM) 622 can be slowlycharged up in at least two methods. In the first method, the shuntswitch 2802 can be turned on the entire period of the start-up process,and charge up V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM) 622 asillustrated with respect to FIG. 28. In the second method, one of moreof the power switches 616, 618 can be always on while the shunt switch2802 can be turned on and off with a programmable duty cycle to slowlybring up V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM) 622 and thusV_(OUT) 304.

In some embodiments, a hybrid regulator can include a soft start-upcircuitry that, in turn, includes using a shunt regulator. FIG. 30illustrates a hybrid regulator having a shunt regulator as a start-upcircuitry in accordance with some embodiments. A soft start-up can beimplemented using switch 2902 and the shunt regulator 3002 couplingV_(IN) 308 and V_(OUT) 304. During start-up, the switch 2902 can beturned off to isolate the inductor 608 from the start-up operation.Thus, the switch 2902 can ensure that the current I_(L) 612 through theinductor 608 can stay at zero until the start-up process is completed.During the start-up process, the shunt regulator 634 can increaseV_(OUT) 304. The step-down regulator 312 can operate in a reverse powertransfer from V_(OUT) 304 powered by the shunt regulator 3002 toincrease V_(N:M) _(_) _(TOP) 620 and V_(N:M) _(_) _(BOTTOM) 622 close toV_(IN) 308. At the end of the start-up process, the series switch 2902is turned on while the power switch 616 and 618 are duty cycled tooperate as a flying switched-inductor converter described with respectto FIG. 6. In some embodiments, the shunt regulator can be coupled toany internal nodes of the step-down regulator. The shunt regulator canbe turned off during a regular operation of the hybrid regulator. Theshunt regulator can include a linear regulator, a switched-capacitorregulator, a buck regulator, or another hybrid regulator.

The terms “a” or “an,” as used herein throughout the presentapplication, can be defined as one or more than one. Also, the use ofintroductory phrases such as “at least one” and “one or more” should notbe construed to imply that the introduction of another element by theindefinite articles “a” or “an” limits the corresponding element to onlyone such element. The same holds true for the use of definite articles.

It is to be understood that the disclosed subject matter is not limitedin its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The disclosed subject matter is capable ofother embodiments and of being practiced and carried out in variousways. Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, systems, methods and media forcarrying out the several purposes of the disclosed subject matter. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the disclosed subject matter.

Although the disclosed subject matter has been described and illustratedin the foregoing exemplary embodiments, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the details of implementation of the disclosedsubject matter may be made without departing from the spirit and scopeof the disclosed subject matter, which is limited only by the claimswhich follow.

We claim:
 1. A voltage regulator configured to receive a first voltage signal and provide a second voltage signal based, at least in part, on the first voltage signal, the voltage regulator comprising: a receiving regulator comprising an inductor, wherein the receiving regulator is configured to receive the first voltage signal at a first terminal of the inductor and to provide an intermediate voltage signal at a second terminal of the inductor based, at least in part, on the first voltage signal; and a step-down regulator comprising a plurality of input terminals and an output terminal, wherein the step-down regulator is configured to receive, at one of the plurality of input terminals, the intermediate voltage signal from the second terminal of the inductor for a portion of a time period, and to provide the second voltage signal at the output terminal based on the received intermediate voltage signal; wherein the step-down regulator is configured to down-convert the intermediate voltage signal at a first conversion ratio from a first one of the plurality of input terminals to the output terminal when the intermediate voltage signal is received at the first one of the plurality of input terminals, and wherein the step-down regulator is configured to down-convert the intermediate voltage signal at a second conversion ratio from a second one of the plurality of input terminals to the output terminal when the intermediate voltage signal is received at the second one of the plurality of input terminals.
 2. The voltage regulator of claim 1, further comprising a plurality of switches configured to couple the second terminal of the inductor to at least one of the plurality of input terminals.
 3. The voltage regulator of claim 2, wherein a first switch of the plurality of switches is configured to couple the second terminal of the inductor to a first input terminal of the plurality of input terminals, wherein a second switch of the plurality of switches is configured to couple the second terminal of the inductor to a second input terminal of the plurality of input terminals, and the first switch and the second switch are turned on in a time-multiplexed manner.
 4. The voltage regulator of claim 3, wherein the step-down regulator is configured to reduce a voltage at the first input terminal by a first amount and reduce a voltage at the second input terminal by a second amount different from the first amount.
 5. The voltage regulator of claim 4, further comprising a controller configured to control a duty cycle of the first switch and the second switch to control the second voltage signal of the voltage regulator.
 6. The voltage regulator of claim 4, wherein the step-down regulator includes a plurality of switched capacitor regulators.
 7. The voltage regulator of claim 3, wherein the receiving regulator further comprises a series switch in series with the inductor, wherein the series switch is configured to decouple the inductor from the first switch and the second switch when the voltage regulator is initially powered up to reduce an inrush current.
 8. The voltage regulator of claim 2, wherein the receiving regulator and the plurality of switches form a flying switched-inductor regulator.
 9. The voltage regulator of claim 2, wherein the step-down regulator and the plurality of switches form a switched capacitor regulator.
 10. The voltage regulator of claim 1, wherein the receiving regulator further comprises a shunt switch that is configured to short the inductor when the voltage regulator is initially powered up to reduce an inrush current.
 11. The voltage regulator of claim 1, further comprising a shunt regulator configured to increase a voltage at the second terminal of the inductor when the voltage regulator is initially powered up to reduce an inrush current.
 12. The voltage regulator of claim 1, further comprising a shunt regulator configured to increase a voltage at one of nodes within the step-down regulator when the voltage regulator is initially powered up to reduce an inrush current.
 13. The voltage regulator of claim 1, wherein the step-down regulator comprises at least one capacitor, and the at least one capacitor is fabricated using a dynamic random access memory (DRAM) fabrication process.
 14. An electronic system comprising: a voltage regulator according to claim 1; and a target load system coupled to the voltage regulator, wherein the output terminal of the step-down regulator in the voltage regulator is coupled to the target load system.
 15. The electronic system of claim 14, wherein the target load system includes a battery and the voltage regulator is configured to receive the first voltage signal from a power line of a Universal Serial Bus and to provide the second voltage signal to the battery to charge the battery using the power line of the Universal Serial Bus.
 16. An electronic system comprising: a voltage regulator according to claim 1, wherein the voltage regulator is configured to operate in a reverse direction in which the output terminal of the step-down regulator in the voltage regulator is coupled to an input voltage source and the first terminal of the inductor in the receiving regulator is coupled to a target load of the voltage regulator.
 17. The electronic system of claim 16, wherein the electronic system operating the voltage regulator in a reverse direction is configured to operate the voltage regulator as a step-up regulator.
 18. The electronic system of claim 17, wherein the output terminal of the step-down regulator in the voltage regulator is coupled to a battery and the first terminal of the inductor in the receiving regulator is coupled to a power line of a Universal Serial Bus.
 19. The regulator of claim 1, wherein the receiving regulator consists of an inductor.
 20. A method of converting a first voltage signal to a second voltage signal using a voltage regulator comprising a receiving regulator and a step-down regulator, the method comprising: receiving, at a first terminal of an inductor in the receiving regulator, the first voltage signal; providing, at a second terminal of the inductor, an intermediate voltage signal based, at least in part, on the first voltage signal; coupling the second terminal of the inductor to a first one of a plurality of input terminals of the step-down regulator and providing the intermediate voltage signal to the first one of the plurality of input terminals; converting the intermediate voltage signal, provided at the first one of the plurality of input terminals, into the second voltage signal, at an output terminal, at a first voltage conversion ratio using the step-down regulator; coupling the second terminal of the inductor to a second one of the plurality of input terminals of the step-down regulator and providing the intermediate voltage signal to the second one of the plurality of input terminals; and converting the intermediate voltage signal, provided at the second one of the plurality of input terminals, into the second voltage signal, at the output terminal, at a second voltage conversion ratio using the step-down regulator.
 21. The method of claim 20, wherein one of the plurality of input terminals is coupled to ground.
 22. The method of claim 20, further comprising coupling, via a first switch for a first duration, the second terminal of the inductor to a first input terminal of the plurality of input terminals, and coupling, via a second switch for a second duration, the second terminal of the inductor to a second input terminal of the plurality of input terminals.
 23. The method of claim 20, further comprising controlling a ratio of the first duration and the second duration to control the second voltage signal.
 24. The method of claim 20, further comprising shorting the first terminal and the second terminal of the inductor using a shunt switch when the voltage regulator is initially powered up to reduce an inrush current.
 25. The method of claim 20, further comprising increasing a voltage at the second terminal of the inductor using a shunt regulator when the voltage regulator is initially powered up to reduce an inrush current.
 26. The method of claim 20, wherein the output terminal of the step-down regulator in the voltage regulator is coupled to an input voltage source and the first terminal of the inductor in the receiving regulator is coupled to a target load of the voltage regulator to operate the voltage regulator in a reverse direction. 